Fire alarm



Oct. 6, 1942. c. K. HUTHSING FIRE ALARM Filed NOV. 29, 1940 INVENTQR 2 u. E1. BY

Patented Oct. 6, 1942 UNITED STATES PATENT OFFICE FIRE ALARM Charles K. Huthsing, Grosse Pointe, Mich.

Application November 29, 1940, Serial No. 367,687

10 Claims.

This invention relates to a novel type of audible fire alarm, and particularly to a bomb type fire alarm in which one or more bombs are discharged automatically either by the heat or flame of the fire,

The main objects of this invention are toprovide an audible fire alarm of simple construction, so designed that it may. be sold at a price within reach of the small home owner; to provide an audible fire alarm which will invariably sound an alarm in the event of a fire in its vicinity; to provide a fire alarm which will sound an alarm in the event of a passing flame, even though the fire does not heat the surrounding atmosphere to the temperature at which the alarm is set to operate; to provide a construction in which the alarm will not be set off by temperatures lower than the predetermined one because of softening of a fusible material employed therein; to provide a fire alarm which may be readily installed without necessitating the services of a skilled mechanic, or electrician; to provide a fire alarm which needs no attention after it is installed until it has sounded an alarm;

and to provide a fire alarm which may be readily and inexpensively prepared for additional service after it has sounded an alarm.

Other objects of the invention will become apparent from the following specification, the accompanying drawing, and the claims hereinafter set forth.

In the accompanying drawing, which illustrates the preferred embodiment of the present invention, and in which like numerals refer to like parts throughout the several views:

Fig. 1 is a View, partly in section and partly in front elevation, of an embodiment of the invention, showing the fire alarm secured in position on a wall.

Fig. 2 is a side elevational View of the same embodiment also showing the alarm secured in position.

Fig. 3 is a sectional View taken at the line 33 of Fig. 1, and looking in the direction indicated by the arrows with the exception of a portion of the upper end adjacent the bracket which is altered to show certain detail and the outer end of the firing pin barrel which is broken away.

Fig. 4 is a sectional view taken at the line 44 of Fig. 1 and looking in the direction indicated by the arrows.

Fig. 5 is a fragmentary view in section showing the position of the parts at the time the bomb is exploded, with the position of certain parts prior to explosion shown in broken lines.

Fig. 6 isan enlarged fragmentary view showing the position of the parts of the fuse assembly prior to the operation of the alarm.

Referring tothe drawing, the fire alarm is described in the position shown, it being clear that the alarm will operate in any position and that the position shown is merely illustrative. The alarm is provided with, a vertical Wall plate or supporting member I provided with a plurality of holes 2 adapted'toreceive any suitable means as screws 3, effective to secure said wall plate to a wall 4 or any other object to which it is desired to secure it. 'A hollow, vertically disposed cylindrical explosion chamber 5 comprises a cylindrical tubular portion 6 and an upper end piece or cap I and a. lower end piece or bottom 8 which cover theopen ends I2 and I3; of the tubular portion 6. The caps l and 8 are held securely over said open ends l2 and I3; by an axially disposed bolt l4 extending throughv an opening I5-in the cap I and threading intoan internally threaded opening Win the cap 8.

The end pieces I and 8 are provided with integral support brackets 9 and HI, respectively,

which are secured to thewall plate I by any suitable means as rivets H, and support the explosion chamber 5 in spaced relation to the wall plate I. The tubular portion 6 is provided with a plurality of axially spaced, circumferentially extending slots H which open toward the wall plate I and are effective to permit the rapid expansion of gases within the explosion chamber 5 without damage to the chamber 5. Holes .58 are provided in the cap 1 adjacent the bracket 9 and constitute additional air vents or means of escape of gases within the explosion chamber. The slots H are internally covered by a flamearresting screen l8 which is preferably cylindrical so that it is held against the tubular portion 5 byits. own spring action and so that it will cover the. slots I! even though it is rotated from its original position. 'The screen [8 should be of sufficiently fine mesh to be efiective to prevent any flame produced by the operation of the alarm from passing through the slots [1.

The tubular portion 6 of the explosion chamber- 5 is also provided with a slot [9 adapted to receive the free end of a rectangular lug 20 struck from the wall plate I and bent to a horizontal position. The free end 21 of the lug 20 is received through the slot l9 and engages the ends of the slot to. prevent rotation of the tubular body 6, thereby assuring that the plurality plate I'.

The upper end piece or cap I is provided with two firing chambers 24 and 25, adapted to receive blank cartridges 2?. It is obvious that there may be more than two or possibly one, but it is preferable to have two or more to provide for the case where the intended hearer is asleep :and the first explosion merely arouses him. Thereupon a second explosion will produce a realization of the existence of the fire. In the preferred construction shown, both firing chambers 24 and 25, their contents and the means for producing the explosion are identical, and only one will be described in detail.

The firing chamber 24 comprises a smaller and inner cylindrical chamber 26, extending outwardly from said explosion chamber 5,-and partially through the cap 'I, and a larger and outer cylindrical axially aligned portion 32 extending through the remainder of the cap I. The chamber 23 is adapted to receive and snugly embrace the blank cartridge 21, which is provided with a radially extending rim 33, at its base end 3 I. The rim 33 overlies the marginal edge of the chamber 23 and prevents the cartridge 27 from passing into the explosion chamber 5. The blank cartridge 2? is of the conventional center fire construction having a percussion cap 34 in the center of its base. The outer and larger portion 32 is provided with a disk-like firing pin guide 33, the inner face 34 of which is recessed at 35 to receive the cartridge base. The guide 33 bears against a shoulder 33 which surrounds the cartridge chamber 23. The firing pin guide 33 is provided with an axial opening 31 which is aligned with the percussion cap 33 when the guide 33 is in position and the outer face 35 is tapered inwardly toward the aperture 31 to guide the firing pin 35 and thereby assure its hitting the percussion cap 34.

The guide 33 is also provided with a circumferentially extending flange 63 adjacent its inner face 34 which aids in positioning the guide 33 in the outer section 32. The larger section 32 of the firing chamber 24 is internally threaded at 39 to receive a firing pin barrel 38, the inner end of which is externally threaded.

The barrel 38 is hollow and cylindrical in form, having its outer end necked down at 43 and provided with a relatively small axial opening 4|. The barrel 38 terminates in a cylindrical portion 32 which is axially slotted at four equi-distantly spaced points, said slots extending from the outer end inwardly. The barrel 33 is adapted to fit over the main body portion of the guide 33 and bear against the circumferentially extending flange 43 of said guide 33, so as to clamp the guide firmly in position.

The barrel 38 encloses a firing pin 45 readily slida'ble therein, and the inner end 48 of said firing pin is pointed and adapted to be received in the aperture 3'! of the firing pin guide '33 and impinge upon the percussion cap 34 of the cartridge 2 The portion of said firing pin 45 adjacent the inner end 48 is adapted to be received within the tapered portion 36 of the firing pin guide 33. The outer end of said firing pin 45 is cylindrical in form and of such smaller diameter as to provide a radially extending shoulder 50. The firing pin 35 is provided with a tapped opening in its outer end adapted to receive the externally threaded inner end of the fuse pin 52 which extends through the axial opening M at the outer end of the barrel 33.

The shank portion of the fuse pin 52 adjacent its outer end is circumferentially grooved such that the outer wall of said groove provides a tapered or cam surface 4'! (see Fig. 6) The shank portion of the fuse pin 52 is received in and releasably secured with respect to the short cylindrical fuse pin holder 53. Said holder 53 has a hole eccentrically countersunk therethrough, the shoulder of said countersunk hole being tapered to provide a cam surface 54 adapted to engage the cam surface 41 and coact therewith to align the countersunk hole of the holder 53 with the fuse pin 52 as the fuse pin 52 is pulled through said hole in the operation of the alarm as shown in Fig. 5. The smaller portion of the countersunk hole is sufiiciently large to permit the fuse pin 52 to move freely therethrough. In the prepared position of the fuse assembly, as shown in Fig. 6, the fuse pin 52 is aligned approximately with the holder 53, a portion of the cam surfaces 4'! and 54 being engaged and the remainder of the eccentrically countersunk hole being filled with any suitable fusible material 60 having a predetermined low melting point. This fusible material 60 serves both to secure the fuse pin 52 with respect to its holder 53 by its cementing action and as a wedge to prevent the movement of the holder 53 with respect to the pin 52 to align the pin 52 with the eccentric hole of the holder 53 when the strength of the bond may be reduced, as by hot weather. The holder 53 engages the outer end of the cylindrical portion 42 of the barrel 38.

Said barrel 38 also encloses a coiled spring 55 which surrounds the fuse pin 52 and the outer end of the firing pin 45, the outer end of said spring 55 bearing against the outer end of the barrel 38 and the inner end bearing against the shoulder 53 of the firing pin 55. Said spring 55 is held in compressed position when the fuse pin 52 is threaded into the, tapped opening 5! of the firing pin 45, by the bonding action of the fusible material securing the fuse pin 52 with respect to the holder 53, the engagement of the cam surfaces 41 and 53, which is assured by the wedging effect of the fusible material 65, and the engagement of the fuse pin holder 53 and the outer end of the cylindrical portion 42 of the barrel 38. The barrel 38 is also provided with two small openings 51 which are effective to equalize the pressure inside and outside said barrel 38 at all times.

The barrel 38 is also provided with a ring 56 of Celluloid or other material of very low kindling point of sufficient quantity to melt said fusible material during its combustion. The ring 53 fits over the cylindrical portion 42 at the outer end of the barrel 38. Said ring 55 provides added protection in that it will be ignited by a passing flame which otherwise might not sufficiently heat the alarm to soften the fusible material securing the fuse pin to the fuse pin holder. As the ring burns, it will heat the fusible material through the cylinder 42 and the axial slots therein, thus setting on the alarm.

In operation the alarm is secured in a. place having the greatest likelihood of fire and in that part thereof which will be heated first,.which is usually near the ceiling. In the event of a fire, the fusible material securing the fuse pin 52 to the fuse pin holder 53 is melted either by the direct heat of the fire or by the heat of the burning ring 56 which has been ignited by the fire. The melting of this material terminates both its cementing and wedging action releasing the pressure upon the spring 55, whereupon it rapidly expands, moving the holder 53 so as to align the eccentric hole therein with the fuse pin 52, as it draws the fuse pin 52 from the fuse pin holder 53', and propelling the firing pin 45 to ward the firing pin guide 33 which guides the pointed end 48 thereof through the aperture 37 and against the percussion cap 34 of the blank cartridge 3'! so as to detonate said cartridge 31.

The alarm is reloaded for subsequent use by removing the barrel 38 and the guide 33, and inserting a fresh cartridge for the exploded one. The barrel assembly is prepared for further use by forcing a new ring 56 over the cylinder 42 if the original ring was destroyed, and by reassembling the elements of the barrel assembly to the positions above described. In so doing, a new fusecombination must be employed in which the fuse pin 52 is releasably secured to the holder 53 as hereinabove described. The use of mechanical means of turning the fuse pin holder 53 in threading the fuse pin into the firing pin should be avoided to prevent destroying the bond of the fusible material.

What is claimed is:

1. In an audible fire alarm, an explosive device comprising a cylinder for receiving a blank cartridge, an expansion chamber communicating with said cylinder for receiving the products of combustion, and temperature controlled means for detonating the blank cartridge.

2. In an audible fire alarm, a cylinder for receiving a blank cartridge, an expansion chamber communicating with said cylinder for receiving the products of combustion, means for automatically firing a cartridge upon said means being heated to a predetermined temperature, and inflammable means associated with and for heating said firing means to cause the firing of the cartridge.

3. A fire alarm comprising a blank cartridge, a firing chamber, and means for automatically firing said cartridge, either upon said fire alarm being heated to a predetermined temperature or upon a flame coming in contact with said means, said means comprising a firing pin, a spring, a fuse pin releasably secured to said firing pin, a fuse pin holder releasably secured with respect to said fuse pin by a fusible material having a predetermined low melting point, and a ring of combustible material having a desired low kindling ppint, so placed as to melt said fusible material during the combustion of said ring.

4. In a fire alarm, a blank cartridge, an explosion chamber, apertures therein to permit the escape of rapidly expanding gases in said chamber, a wire screen adapted to cover said apertures at all times and of such fine mesh as to be effective to prevent the passage of any flame produced by the discharge of said cartridge, a firing chamber adapted to receive said cartridge, and. means for automatically discharging said cartridge upon said fire alarm being heated to a predetermined temperature, said last-named means comprising a firing pin guide, a firing pin barrel, a coil spring therein, a firing pin therein, a fuse pin and a fuse pin holder, said spring being held compressed by said firing pin which is releasably secured to said fuse pin, said fuse pin being releasably secured with respect to said fuse pin holder by a fusible material, which will fuse at said predetermined temperature.

5. In a fire alarm, an automatic releasing mechanism comprising afuse pin, a fuse pin holder, a fusible material of low melting point releasably securing said fuse pin with respect to said fuse pin holder and a quantity of a combustible material of very low kindling point adjacent said fusible material sufficient to melt said fusible material by its heat of combustion.

6. In a fire alarm, an automatic releasing mechanism comprising a fuse pin holder having a countersunk hole therein, a fuse pin having an annular groove therein received in said hole, spring means adapted to withdraw said pin from said holder, and a fusible material disposed substantially within said countersunk hole adapted to releasably secure said pin withrespect to said holder, the shoulder between the larger and smaller portions of said countersunk hole being tapered to afford a cam surface on said holder, a wall of said annular groove being correspondingly tapered to present another cam surface adapted to engage and cooperate with said first mentioned cam surface upon the fusing of said fusible material and the operation of said spring means to move said holder so as to align said fuse pin and said hole.

7. An automatic releasing mechanism comprising a bolt member, a stop member, means supporting said stop member, means applying tension to said bolt member opposing said supporting means, and means including a fusible material wedging said stop member into engagement with said bolt member, said members having coacting faces adapted for wedging engagement.

8. An automatic releasing mechanism comprising a support, a releasable element, a stop member supported on said support, means urging said stop member from engagement with said releasable element, said means applying a tension to said releasable element opposing said support and means including a fusible material wedging said stop member into engagement with said releasable element.

9. In a fire alarm, a blank cartridge, an explosion chamber provided with openings therein, adapted to permit the expansion of gases produced by the firing of said cartridge, said openings being covered by a wire screen adapted to prevent the passage through said openings of flame resulting from the discharge of said cartridge, said explosion chamber also being provided with an opening therein constituting a fir ing chamber adapted to receive said cartridge, and means for automatically firing said cartridge either upon said alarm being heated to a predetermined temperature or upon a flame coming in contact with said last-named means, said last-named means comprising a firing pin guide adapted to fit within said firing chamber, a firing pin barrel, one end of which is adapted to be releasably secured in said firing chamber, the other end of said barrel being provided with an aperture therethrough, said aperture being surrounded by an axially and externally extending cylinder, said cylinder having axially extending slots therein, a ring of combustible material of low kindling point fitted over said cylinder, a spring adapted to operate within said barrel, a firing pin adapted to bear against the end of said spring and a fuse pin and fuse pin holder, said holder being secured to said pin by a fusible material which will melt at said predetermined low temperature, said holder bearing against the outer end of said cylinder, said pin being received through said aperture and the inner end of said pin being secured to said firing pin holding said spring in a compressed position.

10. In a fire alarm of the class described, an explosion chamber comprising two end parts and a central section, slots in said central section adapted to permit the expansion of gases produced by the firing of said cartridge, said slots being covered by a wire screen which is efiective to prevent the passage therethrough of flame resulting from the discharge of said cartridge, brackets formed on the ends of said chamber, a Wall plate provided with screw holes secured to said brackets in spaced relation to said explosion chamber, an opening in said explosion chamber constituting a firing chamber adapted to receive said cartridge, and means for automatically firing said cartridge either upon said alarm being heated to a predetermined temperature or upon a flame coming in contact with said last-named means, said last-named means comprising a firing pin guide adapted to fit within said firing chamber, a firing pin barrel, one end of which is adapted to be releasably secured in said firing chamber, the other end of said barrel being provided with an aperture therethrough, said aperture being surrounded by an axially and externally extending cylinder, said cylinder having axially extending slots, a ring of combustible material of low kindling point fitted over said cylinder, a spring adapted to operate within said barrel, a firing pin adapted to bear against the end of said spring and a fuse pin and fuse pin holder, said holder being secured to said pin by a fusible material which will melt at said predetermined loW temperature, said holder bearing against the outer end of said cylinder, said pin being received through said aperture and the inner end of said pin being secured with respect to said firing pin holding said spring in a compressed position.

CHARLES K. HUTI-ISING. 

